Many surgeries involve the insertion of guidewires into a patient's body. The guidewire may be inserted into the digestive tract, urethra, blood vessels, heart chamber, a body cavity such as the abdominal cavity, or a hollow organ. Typically, an artery is the vessel of interest. The artery could be a relatively large peripheral vessel, a relatively small proximal coronary artery, or an artery of any size in between. The guidewire may include an imaging portion that permits close examination of the site of interest by means of ultrasonic waves. An ultrasonic imaging guidewire may pemit the user to obtain 360 degree (i.e., cross-sectional) acoustic images of the vessel wall to, for example, determine the tissue morphology state of a site of interest, position a therapeutic device, monitor the progress of treatment or observe the site after treatment to determine the course of further treatment.
Often, the guidewire must be positioned at a predetermined site after passing through a complex network of blood vessels. Such placement may require a considerable amount of time. Furthermore, the difficulty and time required for guidewire placement increases with increasing vessel occlusion at later stages of disease. Thus, placement of the guidewire can be a time-consuming and difficult task.
Accordingly, once the physician has taken the time to correctly place the guidewire, it is preferable to maintain the guidewire position. However, it is also desirable to obtain images of the diseased area which may require that the guidewire be axially translated to view the site of interest. Hence, after the physician places the guidewire, the physician needs to move the imaging guidewire back and forth to make a correct diagnosis of the lesion morphology. The problem with advancements and pullbacks of the imaging guidewire is that the physician may lose the correct placement of the guidewire, and have to spend additional time repositioning the guidewire. Thus, there currently exists a need to maintain guidewire positioning while permitting multi-position, real-time imaging.
Furthermore, the back-and-forth movement of the guidewire may damage the patient's vessels. Therefore, there currently exists a need to provide safer guidewire imaging.
A significant problem encountered by physicians is the proper positioning of stents. Stents are often used to prevent lumen closure following bypass surgery and to treat acute vessel closure after angioplasty. It is often extremely difficult for a physician to accurately determine the correct location to deploy a stent, particularly at a bifurcating vessel. Incorrect placement of a stent can lead to "stent jail" and is demonstrated in FIG. 3. As shown in FIG. 3, if the stent 100 is incorrectly placed at a bifurcating vessel location 102, the stent 100 may block the vessel 102 and the physician can no longer access that vessel 102. This is particularly dangerous if the vessel 102 becomes diseased, such as at 104, and access is needed for therapy. Thus, there currently exists a need for easier, multi-position, ultrasonic imaging of the site of interest to assist in accurate placement of a stent.
There also currently exists a need to provide improved imaging capabilities, without losing proper guidewire positioning, so as to efficiently locate the site of interest, to properly position therapeutic catheters such as an angioplasty balloon, and to observe continuously the site or sites of interest. There also exists a need to decrease the complexity and to save time associated with the ultrasonic imaging procedure.